Many drive units such as internal combustion engines in motor vehicles cannot start from their own force. They must first be started by an external power source, the starter, and be brought up to the motor turning rate required for the starting. Only after this can they continue to run on their own power. This required, depending on motor type, stroke volume, bearing friction, etc., a differently great starting torque which must be provided by the starter. This operates, ordinarily over a gear, on a massive inertia mass or a flywheel, which is seated on a shaft of the drive unit--in the case of motor vehicles the crankshaft.
It is a known practice to use a battery-fed direct-current motor as a starter in motor vehicles, which, over a drive pinion, transmits the necessary torque onto the flywheel. Typically, in a direct-current series motor, i.e., an electric direct-current motor, an exciter or stator winding is switched in series with an armature winding. In order to start, the drive pinion of the series motor--under action of a magnetic switch-controlled engaging lever--is brought into engagement with a gear rim seated on the periphery of the flywheel disk. After starting, this connection is again interrupted. A freewheel coupling is arranged between the armature of the series motor and the drive pinion, which is constructed as an overload protection. It is to prevent the possibility that the armature, in the starting of the internal combustion engine, will be driven with an undesirably high turning rate. In other known starters, a rather sophisticated meshing gear provides the mechanical connection between the armature of the series motor and the gear rim of the flywheel in order to facilitate the "meshing" of the pinion into the gear rim.
Accordingly, these known starters are an expensive component that is subject to frequent repair. Also the flywheel is an expensive component since its circumference is provided with the gear rim for engagement with the starter pinion and, otherwise, with makings for the control of the ignition processes in the motor.
It is also a known practice to allocate to the flywheel a noise-reducing rotary vibration eradicator, in order already in this place to combat rotary vibrations. For this, reference is made, for example to EP 0 250 913 A2 or DE 89 07 426.2 U1.
Furthermore, for the state of the art reference is made to the following publications: DE 34 08 311 A1 concerns itself with an electric machine--seated on the crankshaft of a piston motor--in which an inertia mass is seated on a crankshaft and on its circumferential surface is equipped with a toroid winding. Fundamentally comparable with this is the electric machine according to DE 33 01 245 A1. DE 37 37 192 A1 discloses an electric machine in motor vehicle, the rotor of which--over a first coupling with the crankshaft of an internal combustion engine as well as, over a second coupling, with the input shaft of a gear--forms the inertia mass for the driving of the crankshaft. Finally, DE 39 26 054 A1 discloses an electric starter motor for starting an inertia wheel seated on a crankshaft, in which system the inertia wheel is constructed as rotor of a reluctance motor.
DE 21 23 831 B2 concerns a linear motor for the starting of an internal combustion machine, the rotor of which is rigidly joined with a crankshaft of the internal-combustion machine. In addition to the rotor of the linear motor, however, an inertia disk for the starting of the internal-combustion machine is coupled with the crankshaft. DE 22 28 516 B2 is a patent of addition to DE 21 23 831 B2.
Further, EP-A-0 103 821 relates to a sector-form reluctance linear motor, the rotor of which, i.e., its moved base element, is a flywheel of a motor vehicle internal combustion engine. The reluctance linear motor is suited for the starting of the internal combustion engine for the indirect starting by acceleration of the flywheel uncoupled from the internal combustion engine, which wheel is coupled in after reaching a sufficient turning rate for the starting, only by an additional coupling.
Finally, DE 23 16 679 B2 deals with linear motors for the drive of rail-bound vehicles; and from DE 40 27 706, further, there is known a contactless electric drive for wheel-bound vehicles over a drive.
Electric motors such as linear motors utilize the principle of electromagnetic induction, i.e., the Lorentz forces. They operate with the following construction: a stationary base element called ("stator") and a movable base element("rotor"). These elements are spatially and physically separated by a gap, such as an air gap. They, however, are linked to one another by a common magnetic flux passing through the gap. A first base element generates a traveling magnetic primary field, primarily with the use of one or more exciter. A second base element is equipped with one or more electric conductors. The primary field of the first base element permeates over the gap the second base element. A driving force, i.e., the Lorentz force, is generated through linkage with the induced electromagnetic field. The exciter windings may be arranged on the stator or on the rotor without affecting the function of the electric motor.